Internally cooled pressure containment system

ABSTRACT

An internally cooled pressure vessel includes a high pressure cylinder having an inner shell, and a shrink-fit, floating liner. The movement of the liner is restrained by the axial friction force between the liner and the shell. The liner is removable and has cooling grooves that can be cleaned and inspected in site. The end load is restrained by a tie rod frame, including tie rods and end flanges that are positioned at both ends of the cylinder. Pressure is introduced through separate top and bottom manifolds. To cool the vessel, water is pumped into the bottom manifold, travels through the cooling grooves, and flows out the top manifold.

[0001] This patent application claims priority to U.S. Provisionalpatent application Ser. No. 60/213,971 filed on Jun. 23, 2000.

FIELD OF THE INVENTION

[0002] The present invention relates to an internally cooled pressurevessel for use in hot isostatic pressing, and particularly relates to aninternally cooled pressure vessel to solidify powders and heal cracksand voids in castings.

BACKGROUND OF THE INVENTION

[0003] A pressure vessel may include a cylinder, as well as a closurestructure to restrain the end load. The closure structure can beconstructed as a threaded end closure or a frame of various designs.Such frame designs include yoke or plate frames; wire wrapped frames andtie rod frames. The cylinder of the pressure vessel can be of a monowallor a multiple wall construction. When a pressure vessel is externallycooled, a temperature gradient is introduced which can generate stresson the outside diameter of the vessel, leading to fatigue and cracking.Larger, high-pressure vessels are particularly susceptible to thermallyinduced stresses since they have thicker walls. Due to the nature ofheat transfer, a given heat flux (watts per unit area) generates alarger temperature gradient across a thicker wall. This, in turn,induces a higher stress at the outer diameter of the wall. Thisphenomenon increases fatigue and reduces the life of these pressurevessels and may contribute to failures in the field. Pressure vesselswith internal cooling mechanisms are known in the art. However, thesemechanisms are usually employed with penetration of the shell of thevessel. Penetrations in the shell of the vessel are undesirable for anumber of reasons. Pressure vessels known in the art, such as wirewrapped vessels do not lend themselves to complete inspection, visually,ultrasonically, or by magnetic particle inspection.

SUMMARY OF THE INVENTION

[0004] In accordance with the present invention, the pressure vesselincludes a top end flange contacting a top manifold, a bottom end flangecontacting a bottom manifold, and a high-pressure cylinder positionedbetween the top manifold and end flange assembly and the bottom manifoldand end flange assembly. The top manifold is in contact with one end ofthe cylinder and the bottom manifold is in contact with the other end ofthe cylinder. The top end flange covers the top manifold and the bottomend flange covers the bottom manifold. Tie rods are placed intocorresponding tie rod holes disposed in the top and bottom flanges. Thetie rods and flanges effect closure of opposite ends of thehigh-pressure cylinder.

[0005] The high-pressure cylinder includes an inner liner and outershell. Cooling grooves are formed in the exterior side of the liner or,alternatively, the grooves are formed in the interior side of the innershell. Water is pumped into the bottom manifold, travels up through thegrooves and exits through the top manifold.

[0006] The liner is held in place within the cylinder by a slightinterference between the larger outside diameter of the liner and thesmaller inside diameter of the shell. The liner is not held in place byany other mechanism. To install the liner within the cylinder, the shellis heated. After the liner is installed, the shell is then cooled. Theliner is a floating liner, as it is not fixedly attached to any othercomponent of the vessel. The liner can be removed by heating the shellallowing the liner to drop out from the cylinder.

[0007] In use, as the temperature of the liner increases, the watertravels through the cooling grooves in the liner to moderate thetemperature of the shell. By moderating the temperature of the shell,the axial forces on the end of the flanges are reduced and in turn thestresses on the tie rods are thereby reduced.

[0008] A removable flange engages the lower manifold. The lower manifoldengages the lower end flange. A threaded bottom closure engages thelower end flange. When the bottom closure is removed, access to theliner is achieved. When the removable flange on the lower manifold isthen removed, the cooling grooves can be accessed and inspected.Moreover, a high-pressure water-blasting lance can be inserted into thecooling grooves and any fouling can be removed therefrom. In addition,the liner can be removed for cleaning by applying modest heat to theoutside diameter of the shell.

[0009] Given that the liner floats within the cylinder, it exerts onlyminimal axial force on the end flanges and tie rods. This is so, eventhough at elevated temperatures, the liner grows axially. Theshrink-fitted liner is sized to be held in place or restrained by theaxial friction force between the liner and the shell at the liner'supper end. As the liner grows axially, it grows downward into a spacedefined by the removable flange, liner inner, bottom manifold, andbottom closure. Thus, the liner does not come in contact with the lowermanifold reducing pressure on the bottom end flange and tie rods.

[0010] The bottom closure includes a head and a threaded portion. Thethreaded portion can be fully threaded or, in the alternative, thethreads can be interrupted. If interrupted, a fraction of a full turn ofthe head will permit the removal of the bottom closure from the lowerend flange.

[0011] Under load, the end flanges will deform or bend. Sphericalwashers are utilized to prevent the tie rods from bending when the endflange deforms under load. By preloading the tie rods, which restrainthe end load, cyclical stress on such parts is reduced, therebyextending their life and reducing fatigue.

[0012] Accordingly, it is an object of the present invention to providean internally cooled pressure vessel, which is not susceptible to theformation of a temperature gradient across the outer wall of thecylinder.

[0013] It is an additional object of the present invention to provide apressure vessel that accomplishes internal cooling of the shell withoutpenetrations to the shell.

[0014] It is a further object of the invention to provide a pressurevessel that permits inspection, by visual, ultrasonic and magneticparticle means, including the cooling grooves.

[0015] In addition, it is an object of the invention to provide apressure vessel with a floating liner that can be removed and inspected.

[0016] It is also an additional object to provide a pressure vessel thatintroduces pressure through a separate manifold.

[0017] Further it is an object to provide a pressure vessel that avoidstress concentrations due to pressure ports in the shell, closure, andend flanges.

[0018] Lastly, it is an object of the present invention to provide apressure vessel that removes the stress concentration, which occurs atthe root of the first thread in a threaded closure.

[0019] Additional objects, characteristics and advantages of theinvention will emerge from the following description given by way ofnon-limiting illustrative example with reference to the appendeddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a perspective view, with some cut-away portions, of thepreferred embodiment of the subject invention.

[0021]FIG. 2 is a cross-sectional view of the preferred embodiment ofthe subject invention.

[0022]FIG. 3a is an enlarged view of the assembled flanges and lowermanifold, the area circled in FIG. 2, of the preferred embodiment of thesubject invention.

[0023]FIG. 3b is an enlarged view of another section of the assembledtop manifold of the preferred embodiment of the subject invention.

[0024]FIG. 4a is a side view of the bottom flange of the preferredembodiment of the subject invention.

[0025]FIG. 4b is a side view of the bottom closure of the preferredembodiment of the subject invention, showing the relationship of thebottom closure to the bottom flange.

[0026]FIG. 5a is a side cross-sectional view of the bottom flange of thepreferred embodiment of the subject invention, while disengaged from thebottom closure.

[0027]FIG. 5b is a side cross-sectional view of the bottom flange of thepreferred embodiment of the subject invention, while engaged to thebottom closure.

[0028]FIG. 5c is a side view of the bottom flange of the preferredembodiment of the subject invention, with bottom manifold attachedthereto.

[0029]FIG. 6a is a side view of the removable flange of the preferredembodiment of the subject invention.

[0030]FIG. 6b is a side view of a disassembled removable flange andlower manifold of the preferred embodiment of the subject invention.

[0031]FIG. 6c is a cross-section view of the assembled removable flangeand lower manifold of the preferred embodiment of the subject invention.

[0032]FIG. 7a is a perspective view of the bottom manifold of thepreferred embodiment of the subject invention.

[0033]FIG. 7b is cross-sectional side view of the bottom manifold of thepreferred embodiment of the subject invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] A pressure vessel 10 comprising a preferred embodiment of thepresent invention is shown in FIGS. 1 through 7. The pressure vessel 10includes high pressure cylinder 11. Cylinder 11 includes shell 20.Pressure vessel 10 also includes top end flange 14 and bottom end flange26, as well as top end manifold 36 and bottom manifold 24. Cylinder 11is position between top flange 14 and bottom flange 26.

[0035] As shown in FIG. 1 bottom manifold 24 has ports 30. Top manifold36 (not shown) will have port As shown in FIG. 4, bottom end flange 26possess recess 33 for mating with top manifold 36 and bottom manifold24, respectively. As seen in FIG. 1, one end of cylinder 11 is incontact with top manifold 36, while the other end of cylinder 11 is incontact with bottom manifold 24.

[0036] Tie rods 34 are placed in corresponding tie rod holes 12 disposedin top end flange 14 and bottom end flange 26. Tie rods 34 and endflanges 14 and 26, along with bottom closure 40 effect closure ofcylinder 11.

[0037] Disposed within cylinder 11 is liner 16. Cooling grooves 18 aremost preferably formed in liner 16. As one of ordinary skill in the artwill readily appreciate, cooling grooves 18 can be axially machined inshell 20, or by separate pieced lengthwise strips, for example,installed between liner 16 and shell 20. Moreover, cooling grooves 18need not be axial. Alternatively, cooling grooves 18 can be helical,which would necessitate the use of a flexible borescope for inspection,and a flexible water blast lance for cleaning.

[0038] Water is pumped into bottom manifold 24, through one of ports 30and travels through cooling grooves 18 and exits through one of ports 38in top manifold 36.

[0039] Liner 16 is held in place within cylinder 11 in view of a slightinterference between the larger outside diameter of liner 16 and thesmaller inside diameter of shell 20. When shell 20 is heated, liner 16can be installed within cylinder 11. Shell 20 is then cooled. As such,liner 16 is said to be shrink-fit within cylinder 11. In use, as thetemperature of liner 16 increases, the water traveling through coolinggrooves 18 moderates the temperature of shell 20. By moderating thetemperature of shell 20, the axial forces on end flanges 14 and 26, and,in turn, tie rods 34, are minimized. The stresses on tie rods 34 arethereby reduced. Liner 16 floats within cylinder 11. As such, liner 16cannot exert any additional axial force on end flanges 14 and 26 and tierods 34. This is so even though at elevated temperatures, liner 16 growsaxially. Liner 16 is sized to be held in place or restrained by theaxial friction force between liner 16 and shell 20 at the upper end ofliner 16. As liner 16 grows axially, it grows toward, but does not comein contact with lower manifold 24, in view of space 22, as shown in FIG.3.

[0040] Bottom closure 40, having threads 32, threadably engages lowerend flange 26. When bottom closure 40 is removed, access to liner 16, aswell as cooling grooves 18, is achieved. As shown in FIG. 3, whenremovable flange 28 is removed from lower manifold 24, cooling grooves18 can be inspected. A high pressure water blasting lance can beinserting into each of grooves 18 and any fouling can be removedtherefrom. In addition, liner 16 can be removed from cylinder 11 forcleaning by applying modest heat to the outside diameter of cylinder 11.Bottom closure 40 can be fully threaded, as shown in FIG. 4B, or, in thealternative, threads 31 can be interrupted. If interrupted, a fractionof a full turn of closure 32 will permit the removal of bottom closure40 from lower end flange 26.

[0041] Although the best mode contemplated for carrying out the presentinvention has been herein shown and described, it will be apparent thatmodifications and variations may be made without departing from what isregarded as the subject matter of the invention.

What is claimed is:
 1. A pressure vessel comprising: a pressurecontainment with a top end and a bottom end and side walls, forming apressure chamber, said top end and said bottom end being open; saidcontainment having a shell and a liner, a top manifold having a topsection, a bottom section, and a side wall, said side wall having aplurality of ports, said bottom section contacting said top end of saidshell, a bottom manifold having a top section, a bottom section, and aside wall, said side wall having a plurality of ports, said top sectioncontacting said bottom end of said shell, a retainer contacting saidbottom end of said liner, a retainer spring supporting said retainer soas to maintain a space between the liner and said bottom manifold, a topend flange contacting said top end also contacting said top manifold attop section of said containment, and a bottom end flange having a recessfor mating with said lower manifold at the bottom section of saidmanifold, said end flanges having portions defining a plurality ofholes, and a plurality of tie rods with each one of said tie rodsresiding simultaneously within one of said top flange holes and one ofsaid bottom flange holes.
 2. A pressure vessel according to claim 1 inwhich a removable flange is located at the top of said lower manifold ofthe said pressure chamber of said containment.
 3. A pressure vesselaccording to claim 2 in which said removable flange is held in place byat least one removable screw.
 4. A pressure vessel according to claim 1in which the said liner is a floating liner held in place by aninterference between the larger outside diameter of the said liner andthe smaller inside diameter of said shell.
 5. A pressure vesselaccording to claim 4 in which spacers are placed longitudinally betweensaid liner and said shell.
 6. A pressure vessel according to claim 4 inwhich grooves are formed into the interior surface of said shell.
 7. Apressure vessel according to claim 4 in which grooves are formed intothe exterior surface of said liner.
 8. A pressure vessel according toclaim 7 in which said grooves are aligned in an axial direction.
 9. Apressure vessel according to claim 7 in which said grooves are alignedin a helical direction.
 10. A pressure vessel comprising: a pressurecontainment with a top end and a bottom end and side walls, forming apressure chamber, said top end and said bottom end being open; saidcontainment having an shell and a liner, a top manifold having a topsection, a bottom section, and a side wall, said side wall having aplurality of ports, said bottom section contacting said top end of saidshell, a bottom manifold having a top section, a bottom section, and aside wall, said side wall having a plurality of ports, said top sectioncontacting said bottom end of said shell, a retainer contacting saidbottom end of said liner, a retainer spring supporting said retainer soas to maintain a space between the liner and said bottom manifold, a topend flange contacting said top end and having a recess for mating withsaid top manifold said top end flange defining a plurality of holes, abottom end flange substantially annular having a recess for mating withlower manifold said bottom flange defining a plurality of holes a bottomclosure engaging said bottom end flange, and a plurality of tie rodswith each one of said tie rods residing simultaneously within one ofsaid top end flange holes and one of said bottom flange holes, at leastone spherical washer at the each end of said each of said tie rods. 11.A pressure vessel according to claim 10 in which the said liner is afloating liner held in place by a interference between the largeroutside diameter of the said liner and the smaller inside diameter ofsaid shell.
 12. A pressure vessel according to claim 11 wherein aremovable flange is located at the top of said lower manifold of saidcontainment.
 13. A pressure vessel according to claim 12 in which saidremovable flange is held in place by at least one removable screw.
 14. Apressure vessel according to claim 12 wherein said bottom closure isfully threaded.
 15. A pressure vessel according to claim 12 wherein saidbottom closure is interruptedly threaded.
 16. A pressure vesselaccording to claim 15 in which spacers are placed longitudinally betweensaid liner and said shell.
 17. A pressure vessel according to claim 15in which grooves are formed into the inner surface of said shell.
 18. Apressure vessel according to claim 15 in which grooves are formed intothe exterior surface of said liner.
 19. A pressure vessel according toclaim 18 in which said grooves are aligned in an axial direction.
 20. Apressure vessel according to claim 18 in which said grooves are alignedin a helical direction.
 21. A method of inspecting and cleaning apressure vessel said vessel comprising: a pressure containment with atop end and a bottom end and side walls, forming a pressure chamber,said top end and said bottom end being open; said containment having ashell and a liner wherein said liner is a floating liner held in placeby a interference between the larger outside diameter of the said linerand the smaller inside diameter of said shell. wherein grooves areformed into said liner, a top manifold having a top section, a bottomsection, and a side wall, said side wall having a plurality of ports,said bottom section contacting said top end, a bottom manifold having atop section, a bottom section, and a side wall, said side wall having aplurality of ports, said bottom section contacting said bottom end, aremovable flange located the top of said lower manifold, a retainercontacting said bottom end of said liner, a retainer spring supportingsaid retainer so as to maintain a space between the liner and saidbottom manifold, a top end flange contacting said top end and having arecess for mating with said top manifold at top section of saidcontainment said top end flange defining a plurality of holes, a bottomend flange substantially annular having a recess for mating said bottommanifold at the bottom end of said containment, said bottom flangedefining a plurality of holes a bottom closure engaging said bottom endflange, and a plurality of tie rods with each one of said tie rodsresiding simultaneously within one of said top end flange holes and oneof said bottom flange holes, at least one spherical washer at the eachend of said each of said tie rods, wherein said method comprises:removing said bottom closure, removing said bottom manifold, removingsaid removable flange, inserting an inspection device into said grooves,and inserting a cleaning device into said grooves.
 22. The method ofinspection and cleaning of claim 21 further comprising: heating saidcontainment, dropping said liner from within said shell and inspectingand cleaning said liner and said containment.